1. Field of the Invention
The present invention relates to a tool for cutting and shaping the lower edge of a profiled unfinished concrete roofing tile manufactured using the extrusion method, whereby the tool has a tool holder, a cutting insert or tip provided with a cutting edge and a template.
2. Background Information
German Patent 35 22 846 C3, FIGS. 5-7, which corresponds to U.S. Pat. Nos. 5,004,415 and 5,223,200, describes a known tool for cutting and shaping the lower edge of profiled unfinished concrete roofing tiles manufactured using the extrusion method. The tool can be attached by way of a tool holder to a pneumatic cylinder which pneumatic cylinder moves the tool. Bolted to the tool holder is a cutting insert or tip, to which tip a template made of abrasion-resistant plastic is fastened. The tool is conventionally oriented at an angle with respect to the lower, perpendicular transverse plane of the unfinished concrete roofing tile, so that the cutting insert executes an inclined cut, at which cut a short piece is separated from the lower edge of the unfinished concrete roofing tile and the lower edge of the template is deformed.
In the known tool, the force necessary to shape the lower edge using the cutting insert is transmitted by the tool holder to the template, which means that the cutting insert is exposed to a high level of impact and bending stress when the tool is in the inclined position. As the cutting insert penetrates the extremely dense unfinished concrete roofing tile, the cutting insert is also exposed to a severe abrasive stress. Because in the known tool it has been determined that the impact and bending stresses are significantly more critical, the cutting insert of the known tool is manufactured from a tough material which is not very resistant to abrasion, and therefore the useful life of the tool is very short.
To increase the life expectancy of the tool, attempts have been made in which the surface of the cutting insert has been hardened or provided with an abrasion-resistant coating. The results of such attempts, however, have been unsatisfactory, because the abrasion-resistant but brittle coatings crack and ultimately chip off of the cutting insert.